97 lines
3.5 KiB
Go
97 lines
3.5 KiB
Go
// Copyright (c) 2013-2017 The btcsuite developers
|
|
// Use of this source code is governed by an ISC
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package blockchain
|
|
|
|
import (
|
|
"github.com/btcsuite/btcd/database"
|
|
"github.com/btcsuite/btcutil"
|
|
)
|
|
|
|
// maybeAcceptBlock potentially accepts a block into the block chain and, if
|
|
// accepted, returns whether or not it is on the main chain. It performs
|
|
// several validation checks which depend on its position within the block chain
|
|
// before adding it. The block is expected to have already gone through
|
|
// ProcessBlock before calling this function with it.
|
|
//
|
|
// The flags modify the behavior of this function as follows:
|
|
// - BFDryRun: The block index will not be updated and no accept notification
|
|
// will be sent since the block is not being accepted.
|
|
//
|
|
// The flags are also passed to checkBlockContext and connectBestChain. See
|
|
// their documentation for how the flags modify their behavior.
|
|
//
|
|
// This function MUST be called with the chain state lock held (for writes).
|
|
func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block, flags BehaviorFlags) (bool, error) {
|
|
dryRun := flags&BFDryRun == BFDryRun
|
|
|
|
// The height of this block is one more than the referenced previous
|
|
// block.
|
|
blockHeight := int32(0)
|
|
prevNode := b.index.LookupNode(&block.MsgBlock().Header.PrevBlock)
|
|
if prevNode != nil {
|
|
blockHeight = prevNode.height + 1
|
|
}
|
|
block.SetHeight(blockHeight)
|
|
|
|
// The block must pass all of the validation rules which depend on the
|
|
// position of the block within the block chain.
|
|
err := b.checkBlockContext(block, prevNode, flags)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
|
|
// Insert the block into the database if it's not already there. Even
|
|
// though it is possible the block will ultimately fail to connect, it
|
|
// has already passed all proof-of-work and validity tests which means
|
|
// it would be prohibitively expensive for an attacker to fill up the
|
|
// disk with a bunch of blocks that fail to connect. This is necessary
|
|
// since it allows block download to be decoupled from the much more
|
|
// expensive connection logic. It also has some other nice properties
|
|
// such as making blocks that never become part of the main chain or
|
|
// blocks that fail to connect available for further analysis.
|
|
err = b.db.Update(func(dbTx database.Tx) error {
|
|
return dbMaybeStoreBlock(dbTx, block)
|
|
})
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
|
|
// Create a new block node for the block and add it to the in-memory
|
|
// block chain (could be either a side chain or the main chain).
|
|
blockHeader := &block.MsgBlock().Header
|
|
newNode := newBlockNode(blockHeader, blockHeight)
|
|
if prevNode != nil {
|
|
newNode.parent = prevNode
|
|
newNode.height = blockHeight
|
|
newNode.workSum.Add(prevNode.workSum, newNode.workSum)
|
|
}
|
|
b.index.AddNode(newNode)
|
|
|
|
// Undo changes to the block index when running in dry run mode.
|
|
if dryRun {
|
|
defer func() {
|
|
b.index.RemoveNode(newNode)
|
|
}()
|
|
}
|
|
|
|
// Connect the passed block to the chain while respecting proper chain
|
|
// selection according to the chain with the most proof of work. This
|
|
// also handles validation of the transaction scripts.
|
|
isMainChain, err := b.connectBestChain(newNode, block, flags)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
|
|
// Notify the caller that the new block was accepted into the block
|
|
// chain. The caller would typically want to react by relaying the
|
|
// inventory to other peers.
|
|
if !dryRun {
|
|
b.chainLock.Unlock()
|
|
b.sendNotification(NTBlockAccepted, block)
|
|
b.chainLock.Lock()
|
|
}
|
|
|
|
return isMainChain, nil
|
|
}
|